GHG Emissions - Sources

The sources of greenhouse gases (GHG) come from various
sectors including transportation, industrial processes, power generation for
residential consumption, agriculture and deforestation. According to the
United Nations Food and Agriculture Organization (FAO), deforestation
accounts for 25 to 30 percent of the release of GHG [http://www.fao.org/newsroom/en/news/2006/1000385/index.html].
The report states: “Most
people assume that global warming is caused by burning oil and gas. But in
fact between 25 and 30 percent of the
greenhouse gases released into the atmosphere each year – 1.6 billion tonnes
– is caused by deforestation.” From
1990 to 2000, the net forest loss was 8.9 million hectares per year. From
2000 to 2005, the net forest loss was 7.3 million hectares per year.

The ten countries with the largest net loss of forest per
year (2000 – 2005) are: Brazil, Indonesia, Sudan,
Myanmar, Zambia Tanzania, Nigeria, Democratic Republic of the Congo,
Zimbabwe, and Venezuela (combined loss of 8.2 million hectares per year). The
ten countries with the largest net gain of forest per year (2000 – 2005) are:China, Spain, Viet Nam, United States, Italy, Chile,
Cuba, Bulgaria, France and Portugal (combined gain of 5.1 million hectares
per year). [http://www.fao.org/forestry/site/28821/en/]

The following figure (left) shows a generalized source of
GHG from various sources. However, this does not include deforestation
(the number one cause of GHG). Various studies show various differing
contributions by sector, since not all consider the same factors. The
right-hand figure shows emissions by sector from another source using 1996
IPCC data [http://www.idosi.org/aejaes/jaes3(5)/1.pdf].
These are global estimates and do not reflect the fact that GHG contributions
by sector vary regionally (for example, in Washington State where a large
portion of power generation is hydroelectric, and where there is no net
deforestation).

Becoming vegetarian would be more efficient in reducing
greenhouse gases than driving a hybrid car. The United Nations Food and
Agriculture Organization (FAO) released a report in November 2006 [http://www.fao.org/newsroom/en/news/2006/1000448/index.html] that states: “the
livestock sector generates more greenhouse gas emissions as measured in CO2
equivalent – 18 percent – than transport…. the livestock sector accounts for
9 percent of CO2 deriving from human-related activities, but produces a much
larger share of even more harmful greenhouse gases. It generates 65 percent
of human-related nitrous oxide, which has 296 times the Global Warming
Potential (GWP) of CO2…it
accounts for 37 percent of all human-induced methane (23 times as warming as
CO2) ” [http://www.un.org/apps/news/story.asp?NewsID=20772&Cr=global&Cr1=environm
]

The following figure shows the
net flux of carbon to the atmosphere due to land use change (which results
mainly due to deforestation for agriculture and fuel-wood in the tropics and
reforestation in the US). The United States has the largest land use
change carbon sink in the world – i.e. while much of the world is burning its
forests, the US is absorbing the carbon from the atmosphere. This figure
shows: “Cumulative
Emissions of C02 From Land-Use Change measures the total mass of carbon
absorbed or emitted into the atmosphere between 1950 and 2000 as a result of
man-made land use changes (e.g.- deforestation, shifting cultivation,
vegetation re-growth on abandoned croplands and pastures). Positive values
indicate a positive net flux ("source") of CO2; for these
countries, carbon dioxide has been released into the atmosphere as a result
of land-use change. Negative values indicate a negative net flux
("sink") of CO2; in these countries, carbon has been absorbed as a
result of the re-growth of previously removed vegetation.” [http://earthtrends.wri.org/pdf_library/maps/co2_landuse.pdf].

The same report also states: “While the majority of global CO2
emissions are from the burning of fossil fuels, roughly a quarter of the
carbon entering the atmosphere is from land-use change.”

A study published in 2008 reports that China (which was
excluded from the Kyoto requirements) became the largest emitter of CO2 from
fossil fuel combustion and cement production in 2006. (Gregg, J. S., R. J.
Andres, and G. Marland, “China: Emissions pattern of the world leader in CO2
emissions from fossil fuel consumption and cement production”, Geophysical Research Letters35,
2008) [http://www.agu.org/pubs/crossref/2008/2007GL032887.shtml].

The following figures are from that study. The left-hand
figure compares the US annual carbon emissions with China’s since 1950. The
right-hand figure compares the monthly carbon for 2001 – 2007. The study
states: “the
annual emission rate in the US has remained relatively stable between
2001–2006 while the emission rate in China has more than doubled.”

China – the world's largest greenhouse gas
emitter – released its plan on climate change in 2007, supporting the rights
of developing nations to pursue growth. The Chinese spokesman said "The consequences of inhibiting their development
would be far greater than not doing anything to fight climate change … our
general stance is that China will not commit to any quantified emissions
reduction targets".
[www.dw-world.de/dw/article/0,2144,2575639,00.html]

March 15, 2010: “CO2 at new highs despite economic
slowdown: Levels of the
main greenhouse gas in the atmosphere have risen to new highs in 2010 despite
an economic slowdown in many nations that braked industrial output …
Recession in 2009 in many nations has not apparently affected gains.”
[http://www.reuters.com/article/idUSTRE62E2KJ20100315]

The Reuters article quoted above ignores a simple fact: the
increase in CO2 is from the “developing” nations (especially China), not the
“developed” nations that have had the most economic slowdown.

Of course, the alarmists at treehugger.com do their usual
blame game: “After global
emissions stalled following the worldwide recession around 2008--even falling
in some otherwise heavily polluting nations like the US of A--it looks like
everyone can rest assured: we're back on track with CO2 concentrations
steadily a-risin' in the atmosphere.” They purposefully ignore the
facts shown below.